SICKENED by the number of occasions marine thieves were targeting their boats - 16 times during the first six weeks of this season - members of one of the smallest yacht clubs in Poole Harbour, North Haven, fought back by mounting a virtual 24-hour watch on their stretch of water.

"The good thing was that for the two weeks of our night watches at a time we normally take the biggest beating not one of our craft was attacked," said Bill Downey, the club's harbour watch co-ordinator.

"Sadly, within four days of finishing we had four boats broken into in one night," he added.

But at the same time the harbour's marine police unit was also making an extra effort to clamp down on the escalating crime. This led to a "key arrest" being made and the recovery of £20,000-£30,000 worth of stolen marine property - some of it belonging to the North Haven sailors.

"With the one arrest we cleared up more than 30 separate crimes so the whole operation, which involved a lot of work by ourselves, was successful," commented Sgt Mike Stephenson, head of the marine unit.

Whether the absence of crime during the fortnight of the low profile round-the-clock surveillance at North Haven was a direct result of this or was purely coincidental is not known.

But praising the increased police presence, Mr Downey said: "They were brilliant. They seemed to be everywhere. They manned two boats and were out with us until 2am most nights and sometimes all night."

The club would be stepping up its security again next year, he said. And he hoped everyone else in the harbour would do the same.

His message is echoed by Sgt Stephenson, who will be reporting on his unit's success at the next meeting of Poole Harbour Watch, the body formed some three years ago to unite all interests in the harbour in raising public awareness of marine crime.

Harbour Watch chairman, Peter Burt, of the Royal Motor Yacht Club, said it had distributed more than 18,000 yellow cards advising people of the action to take if they saw something suspicious.

"These have made it much easier for people to understand how to get hold of the police and the system has paid off several times this summer," he said.

"What we are trying to do is harden the target by making it more unpleasant for thieves to operate in the harbour."

His own and several other clubs had organised random security patrols and he hoped to persuade them to repeat these.

"We must keep up the impetus," he added.